TF Ripple Effects on Plasma Energy Confinement Time in IR-T1 Tokamak

In this paper we present analysis of the effects of Toroidal Field ripple (TF ripple) on the plasma energy confinement time in IR-T1 Tokamak. For this purpose, a diamagnetic loop with its compensation coil were designed and installed on outer surface of the IR-T1 tokamak. Amplitude of the TF ripple is obtained 0.01, and also the effects of TF ripple on the plasma energy confinement time discussed. In presence of the TF ripple and in low field side of the IR-T1 tokamak chamber (θ = 0), the local value of energy confinement time increased, whereas in the high field side (θ = 180), the energy confinement time decreased.     

Investigation of Effects of Toroidal Field Ripple on Plasma Poloidal Beta in IR-T1 Tokamak

We present an investigation of effect of Toroidal Field (TF) ripple (due to finite number of the toroidal field coils) on the plasma poloidal Beta in IR-T1 Tokamak. For this purpose, array of magnetic probes and also a diamagnetic loop with its compensation coil were designed, constructed, and installed on the outer surface of IR-T1. Amplitude of the TF ripple is obtained 0.01, and also the effect of the TF ripple on the poloidal Beta discussed. In the high field side region of tokamak chamber, the TF ripple effect is decreasing of the poloidal Beta, whereas the low field side has inverse situation.     

RHF Effect on Shafranov Parameter and Shafranov Shift in IR-T1 Tokamak

In this paper we present an experimental study of effects of Resonant Helical Field (RHF) on Shafranov parameter and Shafranov shift in IR-T1 tokamak. For this purpose a four magnetic pickup coils were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the Shafranov parameter and Shafranov shift obtained. On the other hand, the external RHF applied on tokamak plasma and its effects on results measured. Experimental results of measurements with and without RHF (L = 2, L = 3, L = 2 & 3) show that the addition of a relatively small amount of RHF especially L = 3 mode could be effective for improving the quality of tokamak plasma discharge by flatting the plasma current and reducing the Shafranov parameter and Shafranov shift.     

Effects of Resonant Helical Field (RHF) on Equilibrium Properties of IR-T1 Tokamak Plasma

In this paper we present an experimental study of effects of Resonant Helical Field (RHF) on Shafranov parameter and Shafranov shift in IR-T1 tokamak. For this purpose a four magnetic pickup coils were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the Shafranov parameter and Shafranov shift obtained. On the other hand, the external RHF applied on tokamak plasma and its effects on results measured. Experimental results of measurements with and without RHF (L = 2, L = 3, L = 2 & 3) show that the addition of a relatively small amount of RHF especially L = 3 mode could be effective for improving the quality of tokamak plasma discharge by flatting the plasma current and reducing the Shafranov parameter and Shafranov shift.     

Effects of Resonant Helical Field on Plasma Internal Inductance in IR-T1 Tokamak

Measurement of plasma internal inductance is important in tokamak plasma experiments (plasma internal inductance relates to the plasma current profile). In this paper we present an experimental investigation of effects of Resonant Helical Field (RHF) on the plasma internal inductance in IR-T1 tokamak. For this purpose, four magnetic probes and also a diamagnetic loop with its compensation coil were constructed and installed on outer surface of the IR-T1 tokamak, and Shafranov parameter, poloidal Beta, and then the internal inductance determined. In order to investigate the effects of RHF on internal inductance, we measured it in presence and also in absence of different modes of the RHF (L = 2, L = 3, L = 2&3). Experimental results show that L = 3 mode can flat the plasma current and increase the plasma internal inductance.     

Study of Effects of the Effective Edge Safety Factor on the Energy confinement Time in IR-T1 Tokamak

We present study of the effects of effective edge safety factor on the energy confinement time in IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed, and installed on the outer surface of the IR-T1, and then Shafranov parameter is obtained from them. Therefore, the effective edge safety factor obtained. Also, energy confinement time is obtained using diamagnetic loop. Experimental results on IR-T1 show that the maximum energy confinement time relate to the low values of effective edge safety factor (2.5 < q _eff (a) < 2.8). This is agreement with theoretical approach.     

Plasma Internal Inductance in the Presence of External Resonant Fields in IR-T1 Tokamak

In this paper we presented experimental investigation of effects of local limiter biasing (V_biasing = +200 v, V_biasing = +320 v) on the plasma parameters as plasma current, loop voltage, poloidal beta, plasma pressure, plasma energy, plasma resistance, plasma temperature, plasma displacement, Shafranov parameter and plasma internal inductance in IR-T1 tokamak. For these purposes, array of magnetic probes and also a diamagnetic loop have been used. The results show that applied biased voltage V_biasing = +200 v causes to decrease of about 40 % in plasma internal inductance. The plasma resistance and the plasma displacement have been decreased by V_biasing = +200 v. The main result of the application of V_biasing = +200 v is flatting the plasma parameters profiles. In other words, the addition of biasing voltage V_biasing = +200 v to plasma could be effective for improving the quality of tokamak plasma discharge by creating the steady state plasma. The plasma current, plasma pressure, plasma energy, plasma temperature and shift parameter have increased after the application of limiter biasing with V_biasing = +320 v but they decrease rapidly.     

Measurement of Plasma Energy Confinement Time in Presence of Resonant Helical Field in IR-T1 Tokamak

Plasma energy confinement time is one of the main parameters of tokamak plasma and Lawson criterion. In this paper we present an experimental method especially based on diamagnetic loop (toroidal flux loop) for measurement of this parameter in presence of resonance helical field (RHF) in IR-T1 tokamak. For this purpose a diamagnetic loop with its compensation coil constructed and installed on outer surface of the IR-T1. Also in this work we measured the plasma current and plasma voltage from the Rogowski coil and poloidal flux loop measurements. Measurement results of plasma energy confinement time with and without RHF (L = 2, L = 3, L = 2 & 3) show that the addition of a relatively small amount of RHF could be effective for improving the quality of tokamak plasma discharge by flatting the plasma current and increasing the energy confinement time.     

Discrete magnetic probes measurement versus analytical method in determining plasma position in IR-T1 Tokamak

One of the analytical solutions to the inhomogeneous Grad–Shafranov equation (GSE) is based on the well-known Solov’ev equilibrium that corresponds to source functions linear in ψ. The GSE has been solved by this method with constraints over plasma current and poloidal beta using rectangular fixed boundary conditions [1]. In this paper a new analytical solution to GSE by imposing constraints on the plasma current and β_p + l_i/2 is presented. This method is used for plasma position determination in IR-T1 Tokamak by considering linear source functions and circular fixed boundary conditions. Plasma position is also measured by discrete magnetic probes and is compared with the analytical technique. Results comparison shows good agreement for a typical discharge in IR-T1 Tokamak.     

Experimental Study of Effects of the Internal Inductance on the Energy Confinement Time in IR-T1 Tokamak

In this paper we present an experimental study of effects of the internal inductance on the energy confinement time, in IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed, and installed on the outer surface of the IR-T1, and Then Shafranov parameter (asymmetry factor) is obtained from them. On the other hand, also diamagnetic loop were constructed and installed on IR-T1, and poloidal Beta is determined from it. Therefore, the internal inductance obtained. Also, energy confinement time is obtained using diamagnetic loop. Experimental Results show that maximum energy confinement time (which correspond to minimum collisions, minimum microinstabilities, and minimum transport) in IR-T1, relate to the low values of internal inductance (\( 0.61 \, < \, li \, < \, 0.72 \)). This is agreement with theoretical approach.     

Two Semi-Empirical Methods for Determination of Shafranov Shift in IR-T1 Tokamak

In this paper we present two semi-empirical methods for determination of Shafranov shift in IR-T1 tokamak. In the first method, solution of the Grad–Shafranov equation present, and one relation for Shafranov shift obtained, also in second method according to magnetic fields distribution around the plasma, second relation for the Shafranov shift obtained. Based on the two methods, four magnetic pickup coils were designed, constructed, and installed on the outer surface of the IR-T1 tokamak chamber and then Shafranov shift determined from them. Results of the two methods are in good agreement with each other.     

Comparative Measurements of Plasma Position Using Multipole Moments Method and Analytical Solution of Grad–Shafranov Equation in IR-T1 Tokamak

In this paper we present two methods for determination of plasma position in IR-T1 tokamak: a multipole moments method and analytical solution of equilibrium problem or Grad–Shafranov equation. In the multipole moments method a modified rogowski and saddle coils were designed, constructed, and installed on outer surface of IR-T1 tokamak chamber, then displacement of plasma column were measured from them. To compare the plasma position obtained using this method, analytical solution of Grad–Shafranov equation is also demonstrated on IR-T1 tokamak. Results are in good agreement with each other.     

Plasma Magnetic Fluctuations Measurement on the Outer Surface of IR-T1 Tokamak

In this paper we present an experimental investigation of effects of external rotating helical field (RHF) on magnetic field fluctuations around the IR-T1 tokamak chamber. For this purpose, two magnetic pickup coils were designed, constructed, and installed on the outer surface of the IR-T1 tokamak chamber, and then from their output signals after compensation and integration, poloidal and normal components of the magnetic fields measured. Experimental results show that presence of RHF with L = 3 mode can improve the plasma confinement by flatting the plasma current and reducing the amplitude of magnetic field fluctuations.     

Measurement of Plasma Poloidal Beta in Presence of Resonant Helical Field in IR-T1 Tokamak

Precise measurements of poloidal beta and internal inductance are essential for tokamak plasma experiments. In this paper we present an experimental investigation of effects of Resonant Helical Field (RHF) on the poloidal beta in IR-T1 tokamak. For this purpose, a diamagnetic loop with its compensation coil were constructed and installed on outer surface of the IR-T1 tokamak, and then poloidal beta measured. In order to investigate the effects of RHF on the poloidal beta, we measured it with and without introducing of different modes of the RHF (L = 2, L = 3, L = 2 & 3). Experimental results discussed.     

Calculation of Internal Inductance and Poloidal Beta Using Solovev’s Assumption in a Circular Cross Section Tokamak

We calculated the internal inductance and the poloidal beta in a circular cross section Tokamak using Solov’ev assumption in the solution of Grad–Shafranov equation (GSE). GSE is solved by considering linear source functions and fixed boundary conditions. This solution has the three quantities (plasma current I _p , plasma minor radius r _p and $ \beta_{p} + l_{i} /2 $ ) that they are as input data. In two different discharges on IR-T1 Tokamak with this solution, we have shown that the internal inductance at a low value is required to extend the duration of Tokamak plasma discharge that it is consistence with other method.     

Analysis of ripple and error field due to using the ferritic steel insert in EAST

Chinese Experimental Advanced Superconducting Tokamak (EAST) is ITER-like Superconducting (SC) Tokamak with divertor configuration. However, EAST device has 16 toroidal field coils (TFCs) whose ripple amplitude is 0.67% higher than 0.3% of acceptable level of ITER at separatrix point. In order to improve the plasma control and confinement and have more contribution to ITER Physics, it is expected to reduce the TF ripple to ITER acceptable level. In this contribution, it was preliminarily investigated for installation of the appropriate ferristic steel insert inside EAST vacuum vessel to reducing the ripple based on electromagnetic analyses. Results indicated the ripple amplitude could be achieved to the expected level of less than 0.3%. Simultaneously, the error fields introduced due to installation of the ferristic steel insert was analyzed and not beyond scope of physics requirement.     

Electron Temperature Measurement in IR-T1 Tokamak by ECE Diagnostic

A suitable instrument for electron temperature measurement in Tokamak is electron cyclotron emission diagnostic. We used a heterodyne radiometer in Iran-Tokamak-1 (IR-T1) to measure this parameter. This 5 channel system works in K _α-band and has a very fast response time and good resolution frequency for IR-T1 tokamak. This receiver was used outside the Tokamak, perpendicular to B _t, and with second harmonic of X-mode, variation of electron temperature was measured.     

Relations Between the Plasma Diamagnetic Effect and Plasma Basic Parameters in IR-T1 Tokamak

Precise determination of the poloidal Beta, internal inductance, plasma energy, plasma pressure, plasma temperature, plasma resistance, plasma effective atomic number, and plasma energy confinement time are essential for tokamak experiments. In this paper an experimental method especially based on the plasma diamagnetic effect for measurements of these parameters in IR-T1 tokamak are presented. For these purposes a diamagnetic loop with its compensation coil, and also an array of magnetic probes designed, constructed, and installed on outer surface of the IR-T1. Also in this work we measured the Shafranov parameter, plasma current, plasma voltage, and the plasma density by the magnetic probes, Rogowski coil, poloidal flux loop, and the Langmuir probe measurements, respectively.     

A novel technique for the measurement of plasma displacement in IR-T1 tokamak

In this paper we present a novel technique based on poloidal magnetic flux for determination of plasma displacement in IR-T1 tokamak. This instrument consists of a two semicircle wires which installed toroidally on inner and outer sides of tokamak chamber and connected with each other. In order to receive the poloidal flux on Last Closed Flux Surface (LCFS); this instrument installed on polar coordinate so as projection of it on midplane lie on LCFS. Really, this instrument receives the difference between poloidal flux on inner and outer sides of LCFS, which we needed in calculating of the Shafranov shift. Main benefits of our proposed instrument are that it is a simple, solid, and also its output is directly related to the Shafranov shift. Based on this technique we determined the plasma position and to compare the result obtained using this method, multipole moments method is also experimented on IR-T1. Results of the two techniques are in good agreement with each other.     

Comparative Measurements of the Asymmetry Factor in Tokamaks Using the Magnetic Probes,Poloidal and Toroidal Flux Loops

Measurement of the Asymmetry factor (Shafranov parameter) is essential in tokamak plasma experiments. The purpose of this paper is comparing of the magnetic probes, poloidal flux loops, and diamagnetic loops techniques in determination of the Asymmetry factor in tokamaks. For this reason, array of magnetic probes, flux loops, and diamagnetic loop with its compensation coil, were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the Asymmetry factor and poloidal beta measured. Moreover, a few approximate values of the internal inductance for the different plasma current density profiles are also calculated. Experimental results compared.